I turned it on once and tested the water pressure directly on my hand before putting it away in the box without putting it in my mouth, so it's as good as new. Product Description: 【Powerful Water Flow, Cleans Every Corner】The oral irrigator generates water pressure of 60-150psi and a pulse jet water flow of 1500-2500 times/minute to remove dirt. It thoroughly cleans between teeth and in periodontal pockets, removing dirt, food debris, and plaque that brushing can't reach, and it can also powerfully remove debris around orthodontic appliances. Just move the water between your teeth and in your periodontal pockets, and you can clean your mouth in just 2 minutes. 【5 Water Flow Modes, 360-Degree Rotating Nozzle】Equipped with 5 water flow modes, you can select the water flow strength according to the condition of your gums. It has a memory function that remembers the water pressure level used previously, so you can clean with the same water pressure next time. Furthermore, it comes with 3 types of replacement nozzles, a total of 6, and can rotate 360 degrees, allowing for efficient oral care from any angle, making daily interdental cleaning easy. 【Large Capacity Battery, Convenient USB Charging】Equipped with a 2000mAh large-capacity battery, it can be used more than 20 times with a 3-4 hour charge (when used for about 2 minutes daily). USB charging makes it compact and easy to carry, suitable for travel, outdoor events, and home use. 【IPX7 Waterproof Design, Large Capacity Water Tank】Fully waterproof and cordless, it can be used and stored in humid places such as washbasins and bathrooms, and can also be used in the bath. Equipped with a 350ML large-capacity tank, reducing the number of times to refill water. The water tank is transparent, allowing you to see the remaining amount at a glance. The tank can be removed and cleaned, making it easy to clean. *Please refrain from immersing the main unit in water. Important Notes: ① Please charge this product for 3-4 hours before use. ② Make sure the charging panel does not get wet; completely attach the waterproof cap to the charging port when adding water or cleaning.